Comparison of the performance of the activPAL™ Professional physical activity logger to a discrete accelerometer-based activity monitor

The aim of this study was to assess the accuracy of the 'activPAL(TM) Professional' physical activity logger by comparing its output to that of a proven discrete accelerometer-based activity monitor during extended measurements on healthy subjects while performing activities of daily living (ADL). Ten healthy adults, with unrestricted mobility, wore both the activPAL(TM) and the discrete dual accelerometer (Analog Devices ADXL202)-based activity monitor that recorded in synchronization with each other. The accelerometer derived data were then compared to that generated by the activPALTM and a complete statistical and error analysis was performed using a Matlab((R)) program. This program determined trunk and thigh inclination angles to distinguish between sitting/lying, standing and stepping for the discrete accelerometer device and amount of time spent on each activity. Analysis was performed on a second-by-second basis and then categorized at 15 s intervals in direct comparison with the activPALTM generated data. Of the total time monitored (approximately 60 h) the detection accuracies for static and dynamic activities were approximately 98%. In a population of healthy adults, the data obtained from the activPAL(TM) Professional physical activity logger for both static and dynamic activities showed a close match to a proven discrete accelerometer data with an offset of approximately 2% between the two systems. (c) 2006 IPEM. Published by Elsevier Ltd. All rights reserved.